Features of Solution Behavior of Polymer Stars with Arms of Poly-2-alkyl-2-oxazolines Copolymers Grafted to the Upper Rim of Calix[8]arene

Star-shaped polymers with arms of block and gradient copolymers of 2-ethyl- and 2-isopropyl-2-oxazolines grafted to the upper rim of calix[8]arene were synthesized by the “grafting from” method. The ratio of 2-ethyl- and 2-isopropyl-2-oxazoline units was 1:1. Molar masses and hydrodynamic characteristics were measured using molecular hydrodynamics and optics methods in 2-nitropropane. The arms of the synthesized stars were short and the star-shaped macromolecules were characterized by compact dimensions and heightened intramolecular density. The influence of the arm structure on the conformation of star molecules was not observed. At low temperatures, the aqueous solutions of the studied stars were not molecular dispersed but individual molecules prevailed. One phase transition was detected for all solutions. The phase separation temperatures decreased with a growth of the content of more hydrophobic 2-isopropyl-2-oxazoline units. It was shown that the way of arms grafting to the calix[8]arene core affects the behavior of aqueous solutions of star-shaped poly-2-alkyl-2-oxazoline copolymers. In the case of upper rim functionalization, the shape of calix[8]arene resembles a plate. Accordingly, the core is less shielded from the solvent and the phase separation temperatures are lower than those for star-shaped poly-2-alkyl-2-oxazolines with lower rim functionalization of the calix[8]arene.

IL-38 exerts anti-inflammatory and anti-fibrotic effects in thyroid-associated ophthalmopathy

Context Thyroid-associated ophthalmopathy (TAO) is an organ-specific autoimmune disease closely associated with Graves’ disease (GD). IL-38, a novel cytokine in the IL-1 superfamily, has been reported to be involved in the pathogenesis of various autoimmune diseases. Objectives To evaluate the relationship between IL-38 and TAO disease activity and its role in inflammation and fibrosis in TAO. Design/Setting/Participants Blood samples and orbital connective tissues were collected from TAO patients and controls. Orbital fibroblasts (OFs) were isolated from patients with TAO. Main Outcome Measures Enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (IHC), flow cytometry, immunofluorescence, quantitative real-time PCR and western blot analysis were performed. Results Here, we demonstrated that IL-38 levels decreased in the circulation and orbital connective tissues of patients with TAO compared to the controls, and were negatively correlated with the clinical activity score (CAS). In vitro, potent anti-inflammatory and anti-fibrotic effects of IL-38 were observed. Furthermore, we revealed that IL-38 can counteract the phosphorylation of star molecules in multiple classical pathways. Conclusions IL-38 plays a protective role in TAO and is associated with its pathogenesis. Our data suggest that IL-38 may be a promising marker of TAO disease activity and a potential target for TAO therapy.

PEG-POSS Star Molecules Blended in Polyurethane with Flexible Hard Segments: Morphology and Dynamics

A star polymer with a polyhedral oligomeric silsesquioxanne (POSS) core and poly(ethylene glycol) (PEG) vertex groups is incorporated in a polyurethane with flexible hard segments in-situ during the polymerization process. The blends are studied in terms of morphology, molecular dynamics, and charge mobility. The methods utilized for this purpose are scanning electron and atomic force microscopies (SEM, AFM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and to a larger extent dielectric relaxation spectroscopy (DRS). It is found that POSS reduces the degree of crystallinity of the hard segments. Contrary to what was observed in a similar system with POSS pendent along the main chain, soft phase calorimetric glass transition temperature drops as a result of plasticization, and homogenization of the soft phase by the star molecules. The dynamic glass transition though, remains practically unaffected, and a hypothesis is formed to resolve the discrepancy, based on the assumption of different thermal and dielectric responses of slow and fast modes of the system. A relaxation α′, slower than the bulky segmental α and common in polyurethanes, appears here too. A detailed analysis of dielectric spectra provides some evidence that this relaxation has cooperative character. An additional relaxation g, which is not commonly observed, accompanies the Maxwell Wagner Sillars interfacial polarization process, and has dynamics similar to it. POSS is found to introduce conductivity and possibly alter its mechanism. The study points out that different architectures of incorporation of POSS in polyurethane affect its physical properties by different mechanisms.

Conjugated donor–acceptor star molecules: a new concept for substantial dielectric breakdown strength improvement in PVDF films

Star-shaped molecules with donor–acceptor structures can significantly improve the BDS of PVDF terpolymer films.

Deciphering the dynamics of star molecules in shear flow

Under shear flow, star polymers tank-tread. We describe another elongational vibration, “breathing”, and relate it with chains’ and rings’ tumbling.

Synthesis and properties of low bandgap star molecules TPA-[DTS-PyBTTh3]3 and DMM-TPA[DTS-PyBTTh3]3 for solution-processed bulk heterojunction organic solar cells

Two symmetrical planar star shaped organic small molecules TPA[DTS-PyBTTh3]3 (1) and DMM-TPA[DTS-PyBTTh3]3 (2) with TPA and fused TPA core donors, respectively, and three branched DTS-PyBTTh3 units were synthesized and characterized.